Component for the Absorption of Energy on an Impact

ABSTRACT

The present invention relates to a component for the absorption of energy on an impact having a frame as well as having a section located in the frame and connected to the frame, with the section consisting of a multilayer fiber composite or comprising a multilayer fiber composite.

The present invention relates to a component for the absorption ofenergy on an impact. Components of this type serve for the reduction ofkinetic energy on an impact by essentially elastic or, as a rule,plastic deformation of the component. These “energy absorption members”are also termed crash members or crumple members in automobileconstruction. Crash members or crumple members are known in a number ofdifferent embodiments.

DE-OS 2 213 323 relates to a plastically deformable structure whichconsists of a stable-shape hollow body as well as a plasticallydeformable member which is made up of a plurality of sheets which arebonded or welded to one another. The sheets have a loop-shaped regionwhich is located in the hollow body. In the event of an impact, theloop-shaped region passes through the hollow body. The energy to beapplied for this purpose results in the reduction of the kinetic energyand thus in shock absorption. A further portion of the kinetic energy isreduced in that the connection points between the sheets break open.

An energy absorption member is known from DE 41 34 545 A1 in which twosections movable relative to one another are in connection to oneanother by a deformable, semi-rigid and tear-proof material strip. Inthe case of an impact, the kinetic energy is reduced by the release ofthe material strip from one of the surfaces of the sections and is notreduced by a plastic deformation of the sections—at least on an impactof a lower degree—which should bring about the advantage that thesections remain undamaged where necessary.

DE 2 158 086 A1 discloses a crumple member consisting of a plurality oflayers or coats with sections made in wave-like or honeycomb-like form.The layers or coats are arranged perpendicular to the direction ofimpact.

A sandwich structure of a textile preform is known from DE 42 02 589 C1.The manufacture of the structure takes place in that the cover layers ofthe impregnated preform are connected to a base plate and a cover plateprior to curing. A molding pressure is initially exerted onto thisstructure. Subsequently, the spacing between the base plate and thecover plate is increased until the kernel threads are located in aspecific alignment. The curvatures of the kernel threads reducing thesandwich height should be avoided in this manner.

A component on a velour fabric basis is known from DE-OS 37 23 681. Thevelour fabric consists of a technical yarn. It is cured, resinificatedand has intermediate webs which connect the first layer of the fabricwith a second layer. The component is light, comparatively stable,elastically deformable and can be used as a construction member as wellas an insulation member.

EP 0 055 364 A1 discloses a crash protection component for theabsorption of energy by plastic deformation. The component consists ofan open hollow body whose jacket surface has a network of at least onefiber composite. In this connection, the fiber composite is present in aplurality of layers which can delaminate at their mutual intersections.

Previously known fiber composites which have good energy absorptionproperties can only be processed to form components for complexcomponent demands with difficulty. Moreover, there is a lack ofcost-effective and reliable processes for the finishing of thesematerials, in particular with aligned or oriented fibers for the highvolumes typical in mass production. It is the underlying object of thepresent invention to provide an energy absorbing component which is ofmodular construction and can thus also be manufactured cost effectivelywith a complex geometry.

This object is solved by a component having the features of claim 1.Accordingly, the component has a frame as well as at least one sectionlocated in the frame and in connection to the frame, with the sectionconsisting of a multilayer fiber composite or comprising a multilayerfiber composite. The fiber composite thus has two or more layers which,in the event of an impact, substantially absorb the kinetic energy bydelamination, i.e. by separation of the layers.

The shape of the frame and of the section located therein can be asdesired. Complex structures can also be implemented. The frame and/orthe section are preferably made in areal form. The frame can, forexample, have the shape of a hollow body rectangular or square incross-section, with the section extending into its internal space. Otheraspects of the frame can also be implemented.

The section and the frame can be made in one piece or also in a multipleof pieces.

The frame preferably consists of a hollow body bounded by walls andhaving open or closed end surfaces in whose longitudinal direction thesection extends. The section can extend perpendicular to the end facesof the hollow body so that the narrow side of the section can be seen inthe plan view of the end face of the frame. The end face of the frame isto be understood as that side of the frame which is adjacent to theframe walls and forms the base surface or cover surface of the frame.The end faces can be open or be covered by a plate.

The section is preferably made in an areal manner and can be formed, forexample, by one or more plates which can be planar, curved or corrugatedor even folded.

The frame is made as a hollow body of any desired design, preferably anareal hollow body. The section in accordance with the invention islocated in the hollow space formed by the frame and preferably fills thehollow space in the width, height and longitudinal directions.

The section can be made in a simple manner, for example by shaping orfolding. The frame can be made by folding, for example.

The fiber composite of the section and/or of the frame can consist oftwo or more layers of the same or different fiber or reinforcement typein the same or different fiber orientation.

The component in accordance with the invention is preferably orientedsuch that the impact direction lies in a plane formed by the section sothat delamination of the section layers occurs on the impact.

The fiber composite can be a thermoplastic fiber composite. Generally,however, the use of thermosetting plastics is also conceivable.

The frame and the section can consist of the same material or also ofdifferent materials. It is, for example, conceivable that the frame andthe section consist of a fiber composite or comprise such a fibercomposite, with the fiber composite being able to consist of a pluralityof layers of the same or different fiber or reinforcement type in thesame or different fiber orientation.

Combinations of different materials are also conceivable. It isconceivable to provide the frame as a lightweight component and to makethe section from a fiber composite.

The section is preferably made so that it forms two or more chambers inthe frame. In this manner, a multichamber section is created, with thelongitudinal axes of the chambers extending parallel or substantiallyparallel to the walls of the frame in a preferred embodiment of theinvention. The number and shape of the chambers can be any desired. Thechambers preferably have a size which permits the reception of thedelaminated layers of the walls of the section respectively adjacent tothe chamber. This effect results in a growing filling of the chambers asthe degree of deformation increases, whereby a counter-force directedagainst the impact is exerted which results in the additional reductionof kinetic energy.

The section advantageously has mutually connected areal regions whichare alternately in connection to oppositely disposed frame inner sides.The areal regions are preferably connected to one another by webs. Thewebs can stand perpendicular on the walls of the frame to which theareal regions are connected. An embodiment is preferred in which thewebs extend at a different angle than a right angle to the said wall ofthe frame. In this case, an approximately zig-zag-shape section resultsin a plan view of the end face of the frame whose tips are flattened andwhich form areal regions by means of which the section is connected tothe frame.

The connection technique for the connection of section and frame can beany desired. The connection of the section to the frame inner side bymeans of a conventional welding process can be considered, in particularby means of vibration welding, induction welding, radio frequencywelding, ultrasonic welding, radiation welding or diffusion welding.Ultrasonic welding is in particular of importance in a connection metalfiber composite. Other joining techniques than welding, in particular bymeans of riveting, clinching or adhesive bonding, are also conceivable.

Provision is made in a further aspect of the invention for the weld seamto have a varying degree of consolidation. This can apply both to theweld seam connecting the section to the frame and to the weld seamconnecting a plurality of frame parts to one another.

It is particularly preferred for the weld seam consolidation to increaseas the spacing from the impact surface increases. The degree ofconsolidation of the weld seam can increase—preferably constantly orstep-wise—as the spacing from the end face of the frame increases.Provision can accordingly be made for the frame to consist of a hollowbody bounded by walls and having open or closed end faces and for thedegree of consolidation of the weld seam to increase in the longitudinaldirection of the hollow body. The regions of the partial consolidationor of the varying degree of consolidation can extend over the totallength of the weld seam or also only over part regions.

The variation of the degree of consolidation of the weld seam results ina change in the weld quality (weld pressure) so that a moderate initialfailure can be initiated.

The frame can be made in one piece. It is, however, advantageous, forthe frame to be made in a plurality of parts, with the parts forming theframe being able to be connected by means of the connection technique inaccordance with claim 8 or claim 9. It is, for example, conceivable thatthe frame consist of a substantially U-shaped base part which isconnected to a plate which completes the U-shaped base part to form aperipheral frame. The base part can folded over in the end region of thelimbs and the folded over regions can form the contact and connectionsurface for the plate.

The plate preferably consists of the same material as the component.

The section and/or the frame can consist of plastic fiber reinforcedplastic or can comprise it, with the plastic fiber being able to be apolypropylene fiber. In addition to plastic fiber reinforcement, otherreinforcement types such as by means of glass fibers, carbon fibers,aramide fibers, natural fibers or also steel fibers are conceivable.

It is particularly advantageous for the section and/or the frame toconsist of at least regionally partially consolidated fiber composite.The partial consolidation is preferably influenced directly in theshaping process via the component thickness to be set. The degree ofconsolidation of the section and/or of the frame can increase—forexample constantly or also step-wise—as the spacing from the end face ofthe frame increases. The variation of the degree of consolidation or theregions of consolidation can extend over part regions of the section orof the frame or over the total length of the section or frame. Thepartial consolidation can vary on one or both sides of the frame and/orsection. In a preferred embodiment of the invention, the partialconsolidation is made such that the regions facing the impact arepartially consolidated and the degree of consolidation increases as thespacing from the impact surface increases, i.e. in the longitudinaldirection of the hollow space formed by the frame. It can be achieved inthis manner that initially a low energy absorption takes place and anincreasing energy absorption takes place as the degree of deformationrises. The force introduction into the crash component in accordancewith the invention can take place in a defined manner constantly withoutany unwanted indentation-caused initial strong increase of the forcelevel by a direct setting of the degree of consolidation and of theconsolidation transition. Furthermore, the desired delamination behaviorcan be initiated by the direct selection of the consolidation state.

It is furthermore advantageous for a plate terminating an end face ofthe frame to be provided. This can in particular close the end face ofthe frame which faces the impact direction. The plate can consist of afiber composite, preferably of a thermoplastic fiber composite. It canconsist of individual layers reinforced with glass fiber, carbon fiber,plastic fiber, natural fiber or of aramide fiber. Provision can likewisebe made for the plate to divert higher energy amounts from the componentto the outside by partial consolidation and to absorb some of thekinetic energy.

The invention furthermore relates to a vehicle having a component inaccordance with one of the claims 1 to 18. The component is preferablyarranged in the vehicle such that the plane or planes of the sectionreceived in the frame extend in the impact direction. The end face ofthe frame preferably stands perpendicular or substantially perpendicularto the impact direction.

The invention finally relates to the use of a component in accordancewith one of the claims 1 to 18 as a crash member in a vehicle.

Further advantages and details of the invention will be explained withreference to an embodiment shown in the drawing.

FIG. 1: a perspective view of a component in accordance with theinvention;

FIG. 2 a plan view of the component of FIG. 1;

FIG. 3: an enlarged view of the lower end region of the component ofFIG. 2;

FIG. 4: views of a longitudinal section through partially consolidatedsections in different embodiments;

FIG. 5: a schematic view of the force-travel development on an impactfor a crash member of the prior art and a component for the absorptionof energy in accordance with the invention; and

FIG. 6: a perspective view of a component of FIG. 1 having a plateterminating an end face of the component in a partially sectionalrepresentation.

FIG. 1 shows a component for the absorption of energy on an impact inaccordance with the invention in a perspective view. The component has aframe 10 which consists of a component 12 U-shaped in cross-section anda cover plate 16 which completes the base part 12 to form a peripherallyclosed frame 10 with open end faces. The base part 12 consists of arectangular base plate 13 at whose longitudinal sides standing inperpendicular in FIG. 1 the limbs 14 extend which run parallel to oneanother, stand perpendicular to the base plate 13 and are manufacturedby folding. In their end region, folds 15 extending over the totallength of the limbs 14 are provided which extend perpendicular to thelimbs 14 and parallel to the base plate 13. The length of the limbs 14corresponds to the length of the longitudinal sides of the base plate13.

As can further be seen from FIG. 1-FIG. 3, the side of the base part 12disposed opposite the base plate 13 is closed by the cover plate 16. Thecover plate 16 is connected to the folds 15 by means of a conventionalweld process. It has a dimensioning corresponding to the base plate 13.

The base part 12 and the cover plate 16 together form a frame 10 whichis made in box shape and which is closed with the exception of the openend faces disposed at the top and bottom in FIG. 1. Any other designs ofthe frame are also conceivable in addition to the design of the frameshown in FIG. 1.

As can further be seen from FIG. 1 to FIG. 3, a section 20 which dividesthe frame inner space into a plurality of chambers 50 is located in theframe 10.

The section 20 consists of one or more plates shaped by folding orshaping.

The base part 12, the cover plate 16 and the section 20 consist of athermoplastic fiber composite consisting of a plurality of layers of thesame or different fiber type or reinforcement type in the same ordifferent fiber orientation.

The section 20 has the planar strip-shaped regions 22 which can inparticular be seen from FIG. 3 and extend parallel to the base plate 13and the cover plate 16. The regions 22 extend in the longitudinaldirection of the frame 10 and accordingly perpendicular to its endfaces. They serve as joining surfaces at which the frame 10 is connectedto the section 20. The connection takes place by means of a weldingprocess.

The parts of the frame 10 and the profile 20 with the frame 10 cangenerally also be connected to one another by different connectiontechniques.

As can in particular be seen from FIG. 2, the strip-shaped regions 22 ofthe section 20 are alternately connected to oppositely disposed innersides of the frame 10, i.e. alternatively to the base plate 13 and thecover plate 16.

The connection surfaces or joining surfaces of the frame 10 or of theframe 10 and the section 20 are marked by the reference numeral 4 inFIG. 3.

It can furthermore be seen from FIG. 1 to FIG. 3 that the webs 24 of thesection 20 which connected the regions 22 to one another likewise extendin the longitudinal direction of the frame 10 and thus standperpendicular to the frame end face. The webs 24 stand obliquely on thebase plate 13 and cover plate 16 of the base part 12. They include anacute angle with the perpendiculars of the base plate 13 and the coverplate 16. It is also possible to arrange the webs 24 perpendicular tothe base plate 13 and the cover plate 16. Generally, an angle ispossible between the webs 24 and the frame 10 or the base plate 13 andcover plate 16 in the range from 0° to 90°, i.e. an alignment parallelor perpendicular to the frame 10. Furthermore, a varying angle is alsopossible as is present in round or rounded sections.

The length of the regions 22 and of the webs 24 corresponds to thelength of the longitudinal sides of the frame 10, i.e. the upper edge ofthe section 20 visible from FIG. 1 lies in the plane which is formed bythe end face of the frame 10. Furthermore, the section or sections 20also fill the frame 10 in the width and vertical directions as can beseen from FIG. 1.

The section 3 of the embodiment in accordance with FIG. 1 to FIG. 3 issubstantially based on a zig-zag design having flattened tips whichserve as connection points 4 between the section 20 and the frame 10.

The structure in accordance with FIG. 1 to FIG. 3 consists of one ormore open sections 30 which form chambers 50 in the frame 10. Thechambers 50 have open sides which are located at the side of the frame10 at which it has open end faces. The open sides of the chambers 50 andthe end faces of the frame 10 can lie in one plane, for example, or inplanes parallel to one another.

Instead of the embodiment shown, any other desired profiled section suchas a wave-shaped or straight embodiment of the section is conceivable.

The section 20 as also the frame 10 consists of thermoplastic fibercomposite consisting of a plurality of layers of the same or differentfiber type or reinforcement type in the same or different fiberorientation. The section 20 is manufactured by folding or shaping.

The component in accordance with the invention in accordance with FIG. 1to FIG. 3 is installed in a motor vehicle such that the open end faceshown at the top in FIG. 1 forms the impact surface and standsperpendicular or substantially perpendicular to the impact direction. Inthe case of an impact, a delamination of the layers of the fibercomposite, in particular of the section 20, takes place. Delamination isto be understood as the separation of the layers as a consequence of theabsorption of the kinetic energy on the impact. In particular the webs24 of the section 20 are separated into layers on the impact which arepushed in the respectively adjacent hollow chambers 50 of the component.The layers located in a hollow chamber 50 originate from the respectivewebs 24 adjacent to the hollow chambers 50 and increasingly fill thehollow chamber 50 as the impact progresses. This has the consequencethat as the impact progresses, an increasing counter-force is setagainst the impact, which results in a further reduction of the kineticenergy.

FIG. 4 shows representations of a longitudinal section through partiallyconsolidated sections 20 in different embodiments. The intersection lineextends perpendicular to the end face of the frame. The front side ofthe section 20 which faces the impact and is arranged at the top in FIG.4 is partly consolidated and accordingly has a larger thickness and alower density. As can be seen from FIG. 4, at the left, the degree ofconsolidation can increase continuously (FIG. 4, left) or step-wise atone side (FIG. 4, center) or also step-wise at both sides (FIG. 4,right) as the spacing from the impact plane increases. A two-sidedcontinuous variation is also possible. The frame 10 can have aconsolidation corresponding to the section 20 or a partialconsolidation.

The force introduction into the component can take place in a definedmanner constantly without any unwanted indentation-induced first strongincrease of the power level by the direct setting of the consolidationstate and the consolidation transition. The latter is shown by thethinner of the two lines in FIG. 5. The thicker line shows the extent ofthe force level with the deformation path for a component in accordancewith the invention with partly consolidated sections 20. The frame 10can naturally also be made partly consolidated. An additional triggeringor tuning would thus be unnecessary, but can nevertheless be carriedout. A further advantage consists of the fact that the delaminationbehavior can be set directly over the degree of consolidation. Thepartly consolidated regions have a lower density and strength than thefully consolidated regions and therefore set a low counter force againstthe impact.

FIG. 6 shows an embodiment of the component in accordance with theinvention in an aspect which substantially corresponds to FIG. 1 and inwhich one of the open end faces of the frame 10 is closed by a plate 40.The plate 40 can consist of a fiber composite, preferably of athermoplastic fiber composite. It can consist of individual layersreinforced with glass fiber, carbon fiber, plastic fiber, natural fiber,steel fiber or of aramide fiber. Provision can likewise be made for theplate 40 to divert higher energy amounts from the component to theoutside by partial consolidation and to absorb some of the kineticenergy on the impact.

1. A component for the absorption of energy on an impact having a frameas well as having at least one section located in the frame and beingconnected to the frame, with the section comprising a multilayer fibercomposite.
 2. A component in accordance with claim 1, characterized inthat the frame and/or the section is made areally.
 3. A component inaccordance with claim 1, characterized in that the frame comprises ahollow body bounded by walls and having open or closed end faces inwhose longitudinal direction the section extends.
 4. A component inaccordance with claim 1, characterized in that the fiber composite is athermoplastic fiber composite.
 5. A component in accordance with claim1, characterized in that the frame and the section comprise the samematerial.
 6. A component in accordance with claim 1, characterized inthat the section forms two or more chambers in the frame.
 7. A componentin accordance with claim 1, characterized in that the section has arealregions which are alternately connected to oppositely disposed innersides of the frame.
 8. A component in accordance with claim 7,characterized in that the section is connected to the frame inner sideby vibration welding, induction welding, radio frequency welding,ultrasonic welding, radiation welding or diffusion welding to form aweld seam.
 9. A component in accordance with claim 8, characterized inthat the weld seam has a varying degree of consolidation.
 10. Acomponent in accordance with claim 9, characterized in that the framecomprises a hollow body bounded by walls and having open or closed endfaces; and in that a degree of consolidation of the weld seam increasesin a longitudinal direction of the hollow body.
 11. A component inaccordance with 1, characterized in that the section is connected to aframe inner side by riveting, clinching or adhesive bonding.
 12. Acomponent in accordance with claim 1, characterized in that the frame ismade in multiple parts; and in that the parts forming the frame areconnected by means of a weld process, riveting clinching or adhesivebonding.
 13. A component in accordance with claim 1, characterized inthat the section and/or the frame comprise fiber reinforced plastic. 14.A component in accordance with claim 13, characterized in that thesection and/or the frame comprises glass fibers, carbon fibers, aramidefibers, natural fibers or steel fibers.
 15. A component in accordancewith claim 13, characterized in that the section and/or the framecomprise regionally partly consolidated fiber composite.
 16. A componentin accordance with claim 15, characterized in that the frame comprises ahollow body bounded by walls and having open or closed end faces; and inthat a degree of consolidation of the section and/or frame increases ina longitudinal direction of the hollow body.
 17. A component inaccordance with 10, characterized in that the degree of consolidation ofthe fiber composite increases constantly or step-wise.
 18. A componentin accordance with claim 1, characterized in that a plate terminating anend face of the frame is provided.
 19. A vehicle having a component inaccordance with one of the claim
 1. 20. A vehicle in accordance withclaim 19, characterized in that the component is arranged in the vehiclesuch that a plane or planes of the section received in the frame extendparallel to an impact direction.
 21. Use of a component in accordancewith claim 1 as a crash member in a vehicle.